Decoupling finFET capacitors

ABSTRACT

A semiconductor device including field-effect transistors (finFETs) and fin capacitors are formed on a silicon substrate. The fin capacitors include silicon fins, one or more electrical conductors between the silicon fins, and insulating material between the silicon fins and the one or more electrical conductors. The fin capacitors may also include insulating material between the one or more electrical conductors and underlying semiconductor material.

PRIORITY DATA

The present application is a divisional application of U.S. patentapplication Ser. No. 13/362,796, filed Jan. 31, 2012, issuing as U.S.Pat. No. 9,530,901, entitled “DECOUPLING FINFET CAPACITORS”, each ofwhich is hereby incorporated by reference in its entirety.

FIELD

This disclosure relates generally to semiconductor fabrication and, morespecifically to formation of capacitors.

BACKGROUND

A decoupling capacitor is a capacitor used to decouple one part of anelectrical network (circuit) from another. Noise caused by other circuitelements are shunted through the capacitor, reducing the effect noisehas on the rest of the circuit. Decoupling capacitors are often found inanalog areas of an integrated circuit (IC) and may be formed at the sametime as transistors in the IC.

Transistors are formed in both digital and analog areas of an IC.Transistors are typically formed by providing an active area with dopedsource/drain regions in the substrate, a gate insulating layer over thesubstrate, and a gate electrode over the gate insulating layer. Contactsconnect the source/drain regions and gate electrodes with a conductiveinterconnect structure having several horizontal conductive patternlayers and vertical via layers formed within a plurality of inter-metaldielectric (IMD) layers. Capacitor fabrication is integrated into thetransistor fabrication process using various portions of the transistoras a top electrode of the capacitor, capacitor dielectric, and anode andcathode contacts of the capacitor using minimal additional steps.

As transistor design shifts to a three-dimensional design with multiplegates, metal-oxide metal (MOM) capacitor designs are adapted. MOMcapacitors are digitated, multi-finger capacitors separated bydielectrics. The capacitances of these capacitors depend on thedimensions of the conducting portions, which may be metal layers orpolysilicon layers. As IC dimensions shrink, the metal layers orpolysilicon layers become thinner. The capacitance density of theresulting capacitors also decreases, often very significantly, becausethe capacitance depends largely on the geometry of the capacitorstructure. For these MOM capacitors, the capacitance density decreasesabout 30% per technology node.

Decoupling capacitors designs with improved capacitance density that arecompatible with transistor manufacturing processes continues to besought.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a metal-oxide-metal (MOM) capacitorstructure.

FIG. 2A is a perspective view of a fin capacitor in accordance withvarious embodiments of the present disclosure.

FIG. 2B is a perspective view of a portion of the fin capacitor of FIG.2A showing the various capacitances in accordance with variousembodiments of the present disclosure.

FIGS. 3A to 3H are perspective views of various fin capacitors inaccordance with various embodiments of the present disclosure.

FIG. 4 is a flow chart of methods for forming fin capacitors inaccordance with various embodiments of the present disclosure.

FIG. 5 is a flow chart of another method for forming fin capacitors inaccordance with various embodiments of the present disclosure.

DETAILED DESCRIPTION

This description of the exemplary embodiments is intended to be read inconnection with the accompanying drawings, which are to be consideredpart of the entire written description. In the description, relativeterms such as “lower,” “upper,” “horizontal,” “vertical,”, “above,”“below,” “up,” “down,” “top,” and “bottom” as well as derivativesthereof (e.g., “horizontally,” “downwardly,” “upwardly,” etc.) should beconstrued to refer to the orientation as then described or as shown inthe drawing under discussion. These relative terms are for convenienceof description and do not require that the apparatus be constructed oroperated in a particular orientation. Terms concerning attachments,coupling and the like, such as “connected” and “interconnected,” referto a relationship wherein structures are secured or attached to oneanother either directly or indirectly through intervening structures, aswell as both movable or rigid attachments or relationships, unlessexpressly described otherwise. Like items in different figures areindicated by like reference numerals.

As IC dimensions decrease, planar transistors increasingly suffer fromthe undesirable short-channel effect, especially “off-state” leakagecurrent, which increases the idle power required by the device. In a finfield-effect-transistor (FinFET), the channel is surrounded by severalgates on multiple surfaces, allowing more effective suppression of“off-state” leakage current. FinFETs have higher drive currents and aremore compact than conventional planar transistors.

FinFETs use a substantially rectangular fin structure formed generallyin several ways. In a first method, bulk silicon on a substrate isetched into rectangular fin shape by first patterning and depositing ahardmask layer on the bulk silicon. The hardmask forms a patterncovering the top of the fins. The bulk silicon is then etched to formtrenches between the regions covered by the hardmask layer. The trenchesare formed into shallow trench isolation (STI) features by depositing adielectric material, usually silicon oxide. The dielectric material isusually deposited in excess to completely cover the fins and optionallythe hardmask layer if not already removed. The dielectric material isplanarized down to the top surface of the fin/hardmask, and then etchedto a level below the top of the fin so that a portion of the finprotrudes above the STI.

In a variation of the first method, the hardmask for etching in to thebulk silicon is formed by a process using mandrels. A photoresistpattern is formed and used to etch a mandrel pattern. A conformal spacermaterial is then deposited around the mandrel. The conformal spacer isusually formed of a hardmask material forming a spacer sidewall thinnerthan that of the mandrel. The mandrel material between the spacers isthen removed in subsequent etching operations to leave just the spacersbehind. Some of the spacers are then used as a hardmask for etching thesilicon layers below, forming the fin structures. Using themandrel/spacer method, thinner fins that are closer together can beformed. The fins formed using mandrels are thinner than the resolutionof the lithographic tools.

In a second method, the STI features are formed first on bulk siliconmaterial. The bottoms of the trenches between the STI features areexposed bulk silicon. Silicon is then grown in the trenches to form thefins by using, for example, an epitaxial process. Once a desired finheight is reached, then the STI is etched to a level below the top ofthe fin to expose a portion of the fin. The bulk silicon material may bea silicon substrate or a deposited silicon such as silicon-on-insulator(SOI) with a barrier oxide (BOX) layer between the SOI and theunderlying silicon substrate.

Metal-oxide-metal (MOM) capacitors are commonly used in IC chips thatuse finFET structures. FIG. 1 shows a perspective of the electricalconductors of a simple MOM capacitor. Electrical conductors 101 and 103are inter-digitated with each other with a dielectric layer 105 betweenthem. Electrical conductors 101 are connected to one of a cathode oranode electrode of the capacitor and electrical conductors 103 areconnected to the other one of a cathode or anode electrode. A MOMcapacitor can have any number of fingers for electrical conductorsconnected to one electrode. The fingers may overlay one another withdielectric in between. For example, a number of spaced apart layers suchas the structure of FIG. 1 that are each rotated 90 degrees from eachother may be used. The electrical conductors 101 and 103 may be metallines or polysilicon lines that are formed over a silicon substrateduring transistor manufacturing. As metal lines and polysilicon linesbecome thinner, the capacitance density of MOM capacitors decreases, byas much as 30% per technology node. The decrease capacitance density isaccompanied by a greater demand for capacitance as greater drive currentand smaller size allows more circuitry to be packed into an area.

The present disclosure pertains to a novel fin capacitor that hasenhanced capacitance density over comparable sized MOM capacitors and iscompatible with the FinFET manufacturing process. FIG. 2 is aperspective view of a fin capacitor 200 in accordance with variousembodiments of the present disclosure. The fin capacitor 200 includesfirst electrical conductors 203/207 connected to one of a cathode oranode electrode (not shown), second electrical conductors 201 connectedto another of a cathode or anode electrode (not shown), and insulatingmaterial 205/209 between the electrical conductors 203/207 and 201.

The first electrical conductors 203/207 are made of silicon material.Together, the electrical conductors 203/207 connect to either thepositive or negative electrode of the fin capacitor. Electricalconductors 203 are silicon fins formed during FinFET formation processesconnected to silicon substrate 207. In certain embodiments, the siliconfins 203 are formed out of a silicon substrate by etching a siliconsubstrate between a hardmask or using a mandrel process as describedabove and etching between spacers formed around mandrels. In otherembodiments, the silicon fins 203 are grown on the silicon substrate 207in trenches formed between the silicon substrate and an oxide layer.

The insulating material 205/209 are dielectrics around which theelectrical field for the fin capacitor is formed. The insulatingmaterial 209 is formed during the silicon fin formation process eitheras the shallow trench isolation (STI) deposited after fins are formed orthe STI between which the silicon fins are grown. The insulatingmaterial 209 is usually silicon oxide or any other STI material. OtherSTI material may include silicon oxynitride, silicon nitride, carbondoped silicon oxide or any other dielectric material used during the finformation process. The insulating material 205 may be the same materialas insulating material 209 deposited together with insulating material209 or in a subsequent operation. For example, the insulating material205 and 209 together may be the STI forming the trenches from which thefins are grown. In another example, the insulating material 205 may bedeposited after STI material 209 is formed during the fin formationprocess. Further, the insulating material 205 may also be differentmaterials deposited after the STI material 209 is formed during the finformation process. In some instances, the insulating material 205 mayhave a silicon oxide with a different oxygen content or a siliconoxynitirde material over the silicon oxide 209. In other cases, theinsulating material 205 may include air.

The second electrical conductors 201 are also formed as part of theFinFET formation process. The electrical conductors 201 may be a metallayer within the FinFET structure (MO layer), a metal layer above theFinFET structure (M1 layer), or a polysilicon layer deposited as part ofthe FinFET gate formation process. The electrical conductors 201 areconnected to either the positive or negative electrode of the fincapacitor. Depending on the size of the fin capacitor, a number ofelectrical conductors 201 may be connected together. The 5 electricalconductors 201 of FIG. 2 may be connected as one or two or three fincapacitors. The electrical conductors 201 may be made of any metal,alloy, or compound commonly found in semiconductor processing. In someembodiments, the M0 or M1 layer may be made of tungsten, tantalum,titanium or copper. Other materials include TiN, WN, TaN, Ru, Ag, Al,TiAl, TiAlN, TaC, TaCN, TaSiN, Mn, Ru, Co, and Zr. The electricalconductors 201 may also be at any elevation relative to the silicon fins203 as long as it is between the silicon fins 203 from a top view and isseparated from the silicon fins 203 by a capacitor dielectric materialsuch as insulating material 205 and 209.

The capacitance, or the ability to store electrical energy, of the fincapacitor may be derived from any of two electrical conductors connectedto oppositely charged electrodes as long as there is no directelectrical conduction between them, as is illustrated in FIG. 2B for aportion of the fin capacitor 200. Capacitance is found in many ways. Onesuch way is an overlap capacitance 213 found between electricalconductor 201 and adjacent silicon fin 203 when a bottom of theelectrical conductor 201 is not above a top of the silicon fin 203. Whenthe electrical conductors 201 and 203 are exposed to opposite charges,an electrical field develops between them in a form of overlapcapacitance 213. Note that each electrical conductor 201 and eachsilicon fin 203 can have two neighboring electrical conductors and formtwo overlap capacitances 213 each. Another overlap capacitance (215) isfound between the electrical conductor 201 and the underlying siliconsubstrate 207. Another capacitance is fringe capacitance 217 foundbetween an edge or outside perimeter of the electrical conductor 201 anda non-overlapping portion of the silicon fin 203. The overallcapacitance of the fin capacitor is a function of all the variouscapacitances found between components of the fin capacitor.

As compared to the MOM capacitor of FIG. 1, the fin capacitor formedfrom the same FinFET manufacturing process has a much higher capacitancedensity. The fin capacitor structure decreases the pitch betweenelectrical conductors (fingers) connected to the same electrode. In oneexample, the distance between electrical conductors 103 of FIG. 1 may beabout 160 nanometers (nm) and the distance between electrical conductors203 of FIG. 2 may be about 100 nm. This pitch difference can increasethe capacitance density by about 75%. The space between oppositeelectrical conductors is also decreased. In the example, the distancebetween electrical conductors 103 and 105 in FIG. 1 may be about 60 nmand the shortest distance between electrical conductors 203 and 201 ofFIG. 1 may be about 30 nm. The spacing difference can increase thecapacitance density by almost 100%. A modeling of the total capacitancedensity increase results in an increase of 238% over the MOM capacitorformed in the same area. As transistor dimensions continue to decrease,the difference in capacitance density for the different capacitorstructures would only increase as the spacing between electricalconductors becomes even closer together.

FIGS. 3A to 3H shows various embodiments of a fin capacitor inaccordance with the present disclosure. In FIG. 3A, the electricalconductor 301 is formed directly over another electrical conductor 311.The electrical conductors 301 and 311 may be formed of a same material,such as two different layers of metal layer M0, or be formed ofdifferent materials. For example, the electrical conductor 311 may beformed of polysilicon with electrical conductor 301 formed of a metal,alloy, or metal containing compound. The electrical conductors 301 and311 are connected (not shown in FIG. 3A) to one of an anode or cathodeelectrode for each fin capacitor. Capacitance may be found betweenelectrical conductors 301 and 303, between electrical conductors 311 and303, between electrical conductors 311 and 307 in any of the capacitancetypes discussed. Insulating layers 305 and 309 are disposed between theelectrical conductors 301/311 and 303/307.

In other embodiments, more than two layers of conductors may be usedbetween the silicon fin conductors 303, as shown in FIG. 3B. The fincapacitor of FIG. 3B includes a 3 layer electrical conductor stack 321,311, and 301 between the fin conductors 303. While FIG. 3B shows that atop surface of the stack is coplanar with top of the fin conductors 303,a portion of the stack may protrude the plane formed by the top of thefin conductors 303. Conversely, the top of the stack may also beembedded below the plane formed by the top of the fin conductors 303.The electrical conductors 301, 311, 321 may be formed of a samematerial, such as two different layers of metal layer MO plus one layerof metal layer M1, or be formed of different material. For example, theelectrical conductor 321 may be formed of polysilicon with electricalconductors 311 and 301 formed of a metal, alloy, or metal containingcompound. The electrical conductors 301, 311, and 321 are connected (notshown in FIG. 3B) to one of an anode or cathode electrode for each fincapacitor. Capacitance may be found between electrical conductors 301and 303, between electrical conductors 311 and 303, between electricalconductors 321 and 303, between electrical conductors 321 and 307 in anyof the capacitance types discussed. Insulating layers 305 and 309 aredisposed between the electrical conductors 301/311/321 and 303/307. Insome embodiments, the first electrical conductor layer 321 may be formeddirectly on the insulating material layer 309 without an interveninginsulating material 305.

FIG. 3C shows another embodiment where two layers of conductors are usedbetween the fin conductors 303. However, as opposed to the fin capacitorof FIG. 3A, the electrical conductors 301 and 323 do not directlycontact each other. Insulating material 305 is disposed between theelectrical conductors 301 and 323. The electrical conductors 301 and 323may be formed of a same material or different material, such as twodifferent layers of metal layer M0, or one of polysilicon and one of ametal, alloy, or metal containing compound. For example, the electricalconductor 323 may be formed of polysilicon with electrical conductor 301formed of a metal. The electrical conductors 301 and 323 are connected(not shown in FIG. 3C) to one of an anode or cathode electrode for eachfin capacitor. Capacitance may be found between electrical conductors301 and 303, between electrical conductors 323 and 303, and betweenelectrical conductors 323 and 303 in any of the capacitance typesdiscussed. Insulating layers 305 and 309 are disposed between theelectrical conductors 301, 323, and 303/307. Note that in the embodimentof FIG. 3C, no capacitance is found between electrical conductors 301and 323 even though they are separated by a dielectric because they areconnected to the same electrode.

FIG. 3D shows a fin capacitor embodiment where a bottom surface of theelectrical conductor 331 is at the same plane or higher than a planeformed by the tops of the fin conductors 303. The electrical conductor331 may be a metal layer such as M1 formed of a metal, alloy, or a metalcontaining compound. The electrical conductors 331 are connected (notshown in FIG. 3D) to one of an anode or cathode electrode for each fincapacitor. Capacitance may be found between electrical conductors 331and 303 and between electrical conductors 331 and 307 in some of thecapacitance types discussed. For example, overlap capacitance may befound only between electrical conductors 331 and 307. Insulating layers305 and 309 are disposed between the electrical conductors 331 and303/307.

FIG. 3E shows a fin capacitor embodiment combining features of the fincapacitor of FIG. 3C and 3D. The fin capacitor of FIG. 3E includes twoor more electrical conductor layers (331 and 321) where some of theelectrical conductor layers do not directly contact each other and atleast a portion of the electrical conductor 331 protrudes above a planeformed by the tops of the fin conductors 303. The electrical conductor331 may be a metal layer such as M1 formed of a metal, alloy, or a metalcontaining compound. The electrical conductor 321 may be formed ofpolysilicon or a metal, alloy, or a metal containing compound. Theelectrical conductors 321 and 331 are connected (not shown in FIG. 3E)to one of an anode or cathode electrode for each fin capacitor.Capacitance may be found between electrical conductors 331 and 303,between electrical conductors 321 and 303, and between electricalconductors 321 and 307 in any of the capacitance types discussed.Insulating layers 305 and 309 are disposed between the electricalconductors 331, 321, and 303/307. In some embodiments, the firstelectrical conductor layer 321 may be formed directly on the insulatingmaterial layer 309 without an intervening insulating material 305. Notethat in the embodiment of FIG. 3E, no capacitance is found betweenelectrical conductors 331 and 321 even though they are separated by adielectric because they are connected to the same electrode.

FIG. 3F shows a fin capacitor embodiment where at least a portion of theelectrical conductor 341 protrudes above a plane formed by the tops ofthe fin conductors 303. The electrical conductor 331 may be one or moremetal layers such as M0 and/or M1 formed of a metal, alloy, or a metalcontaining compound. The electrical conductors 341 are connected (notshown in FIG. 3F) to one of an anode or cathode electrode for each fincapacitor. Capacitance may be found between electrical conductors 341and 303 and between electrical conductors 341 and 307 in any of thecapacitance types discussed. Insulating layers 305 and 309 are disposedbetween the electrical conductors 341 and 303/307. In some embodiments,the electrical conductor layer 341 may be formed directly on theinsulating material layer 309 without an intervening insulating material305.

FIG. 3G shows fin capacitor embodiments having a spacer material 325between the electrical conductors 341 and fin conductors 303. The spacermaterial 325 is an insulating material that may or may not be the sameas the insulating materials 305 and 309. A spacer may be depositedduring FinFET manufacturing process around a gate structure. For the fincapacitor, the spacer material 325 is deposited over exposed fins 303and insulating material 309. The spacer material may include siliconnitride or silicon oxide and may be formed in multiple layers. WhileFIG. 3G shows only the spacer material 325 between the electricalconductor 341 and fin conductor 303, another insulating material, suchas insulating material 305, may also be disposed between the spacer 325and the electrical conductor 341.

Portions of the spacer material over the tops of the fins and in thebottom of the trench between the fins may be etched away, leaving theportion on the fin sidewalls. In some embodiments, the portions of thespacer material over the fins 303 are removed in subsequent processingbut the portions in the bottom of the trench between the fins may not beremoved.

The electrical conductor 341 is then formed between the spacers in oneor many layers comprising a same or different material. In certainembodiments of FIG. 3G, the insulating material 305 is optional (i.e.,when the electrical conductor 341 is formed directly over the insulatingmaterial 309). The electrical conductors 341 are connected (not shown inFIG. 3G) to one of an anode or cathode electrode for each fin capacitor.Capacitance may be found between electrical conductors 341 and 303 andbetween electrical conductors 341 and 307 in any of the capacitancetypes discussed.

FIG. 3H shows a variation of the fin capacitor embodiment of FIG. 3Gwhere the electrical conductor 343 is embedded within insulatingmaterial 305. The electrical conductor 343 may include one or morelayers of polysilicon, metal, alloy, or metal-containing compounds. Thespacer material 325 is formed as described in association with FIG. 3G.After the electrical conductors 343 are formed, an insulating material305 is formed over the electrical conductors 343. The electricalconductors 343 are connected (not shown in FIG. 3H) to one of an anodeor cathode electrode for each fin capacitor.

The embodiments of fin capacitor shown in FIGS. 2 and 3A to 3H inaccordance with various embodiments of the present disclosure are merelyexamples and are not meant to be an exhaustive list. Additionalembodiments may be envisioned by one skilled in the art using a siliconfin based transistor manufacturing process. The number of electricalconductor layers, interconnect structure, and insulating materialselection are some example parameters that may vary according to designand process needs without affecting the spirit of the presentdisclosure.

The present disclosure also pertains to a method of forming the fincapacitors. As discussed, the method of forming the fin capacitors iscompatible with the FinFET manufacturing process such that little or noadditional steps are required to form the fin capacitors. FIG. 4 is aflow chart of methods for forming fin capacitors in accordance withvarious embodiments of the present disclosure. In operation 402, asilicon substrate is provided. The silicon substrate may be a baresilicon wafer or a substrate having various processes already performedthereon. For example, the substrate may include silicon formed in asilicon-on-insulator (SOI) process or may have been subjected to varioussurface treatment and doping operations.

Silicon fins and an oxide layer are formed in operation 404. The oxidelayer is formed between the silicon fins on the silicon substrate. Thesilicon fins and the oxide layer are formed as part of the FinFETmanufacturing process as described above. In operation 406 a firstelectrical conductor is formed between some of the silicon fins over theoxide layer where the fin capacitors are formed. The first electricalconductor may be polysilicon grown as a part of the FinFET gateformation process or metal, alloy, or metal-containing compoundsdeposited as part of the M0 or M1 layer formation process. Theelectrical conductor is formed between the silicon fins in a top viewand is parallel to the silicon fins.

In operation 408, an insulating layer is formed between the firstelectrical conductor and the silicon fins. The insulating layer may be adielectric material deposited as part of the interconnect metaldielectric or as part of the FinFET gate dielectric. In certainembodiments, a fin capacitor is formed once the silicon fins and theelectrical conductors are connected to their respective electrodes.

In embodiments where more than one electrical conductor layer is used inthe fin capacitor, optional operations 410, 412, and/or 414 may beincluded. Variations include where only operation 410 is performed,where both operations 410 and 412 are performed, where all threeoptional operations are performed, where operations 410 and 414 areperformed, and various orders of performing these operations.

In operation 410, a second electrical conductor is deposited over thefirst electrical conductor. Note that this operation may be performedbefore or after operation 408 of forming an insulating layer, dependingon whether the second electrical conductor is to directly contact thefirst electrical conductor, as in embodiments of FIGS. 3A and 3B, or beseparated from the first electrical conductor, as in embodiments ofFIGS. 3C and 3E.

In operation 412, a second insulating layer may be deposited over thesecond electrical conductor. In operation 414, a third electricalconductor may be deposited over the second electrical conductor with orwithout intervening insulating layer.

The various electrical conductors may be deposited using processes suchas sputtering, chemical vapor deposition, electroplating, electrolessplating, and electron beam deposition. The conductors may be depositedfirst and unwanted portions removed in subsequent processes or portionsof the work product may be masked using a photomask before deposition.Further, selective deposition methods may be used to avoid having to usea photomask.

The various insulating materials may be deposited using differentchemical vapor deposition processes. Depending on the material andgeometry, one skilled in the art can select the appropriate process todeposit the insulating materials.

FIG. 5 is a flow chart of methods for forming fin capacitors inaccordance with various embodiments of the present disclosure.Operations 501 and 503 are the same as operations 402 and 404 of FIG. 4.In operation 505, a spacer is formed on the sidewalls of some of thesilicon fins where the fin capacitors are formed. The spacer around thefins may be formed during the FinFET gate formation process at the sametime the spacers are formed around the FinFET gate.

In operation 507, a first electrical conductor is deposited between thespacers over the oxide layer. If the spacer is formed with the gateformation process, the first electrical conductor may be metal, alloy,or metal-containing compounds deposited as part of the M0 or M1 layerformation process. If the spacer is formed before the gate formationprocess, the first electrical conductor may be additionally apolysilicon material. The electrical conductor is formed between thesilicon fins in a top view and is parallel to the silicon fins. In someembodiments, the spacer is the only capacitor dielectric between theelectrical conductor and the fin conductor. In other embodiments,another insulating material is deposited between the first electricalconductor and the spacer in operation 509.

Just as operations 410, 412, and 414 from the process of FIG. 4 areoptional, one or more operations 509, 511, and 513 may be includedand/or in different orders of performance. In one embodiment, operation509 is performed. In another embodiment, operation 511 is performed. Instill other embodiments, operations 511 and 513 are performed. In yetother embodiments, all three operations are performed.

In operation 511, a second electrical conductor is deposited over thefirst electrical conductor. Note that this operation may be performedbefore or after operation 509 of forming an insulating layer, dependingon whether the second electrical conductor is to directly contact thefirst electrical conductor or is to be separated from the firstelectrical conductor. In operation 513, a third electrical conductor maybe deposited over the second electrical conductor with or withoutintervening insulating layer.

The various electrical conductors may be deposited using processes suchas sputtering, chemical vapor deposition, electroplating, electrolessplating, and electron beam deposition. The conductors may be depositedfirst and unwanted portions removed in subsequent processes or portionsof the work product may be masked using a photomask before deposition.Further, selective deposition methods may be used to avoid having to usea photomask.

The various insulating materials may be deposited using differentchemical vapor deposition processes. Depending on the material andgeometry, one skilled in the art can select the appropriate process todeposit the insulating materials.

The foregoing has outlined features of several embodiments so that thoseskilled in the art may better understand the detailed description thatfollows. Those skilled in the art should appreciate that they mayreadily use the present disclosure as a basis for designing or modifyingother processes and structures for carrying out the same purposes and/orachieving the same advantages of the embodiments introduced herein. Itis understood, however, that these advantages are not meant to belimiting, and that other embodiments may offer other advantages. Thoseskilled in the art should also realize that such equivalentconstructions do not depart from the spirit and scope of the presentdisclosure, and that they may make various changes, substitutions andalterations herein without departing from the spirit and scope of thepresent disclosure.

What is claimed is:
 1. A method of fabricating a semiconductor deviceincluding a fin capacitor, comprising: forming a first silicon fin and asecond silicon fin, wherein the first and second silicon fins are twoadjacent silicon fins extending from and above a surface of a substrate,wherein each of the two adjacent silicon fins has a first sidewall andan opposing second sidewall, the first and second sidewalls extendingfrom the surface of the substrate; forming a first insulating materialover the substrate, and extending from an interface with the firstsidewall of the first silicon fin to an interface with the firstsidewall of the second silicon fin; forming an electrical conductor overthe first insulating material and between the two adjacent silicon finswherein a top surface of the two adjacent silicon fins and a top surfaceof the electrical conductor are coplanar; and depositing a secondinsulating material over the first insulating material and extendingbetween the first sidewall of a first silicon fin of the two adjacentsilicon fins and the electrical conductor and also extending between thefirst sidewall of a second silicon fin of the two adjacent silicon finsand the electrical conductor, thereby providing for a capacitance to beformed between each of the two adjacent silicon fins and the electricalconductor.
 2. The method of claim 1, wherein the forming the firstinsulating material includes depositing a first composition and thedepositing a second insulating material different than the firstinsulating material.
 3. The method of claim 1, wherein the forming theelectrical conductor includes forming a plurality of electricalconductors.
 4. The method of claim 3, wherein the forming the pluralityof electrical conductors includes forming a first electrical conductorportion and a separate, overlying second electrical conductor portionwherein the top surface of the electrical conductor is defined by thesecond electrical conductor portion.
 5. The method of claim 1, whereinthe depositing the second insulating material extending between thefirst sidewall of a first silicon fin of the two adjacent silicon finsand the electrical conductor includes extending from an interface withthe first sidewall of the first silicon fin to an interface with asidewall of the electrical conductor; and wherein the depositing thesecond insulating material extending between the first sidewall of thesecond silicon fin of the two adjacent silicon fins and the electricalconductor includes extending from an interface with the first sidewallof the second silicon fin to an interface with another sidewall of theelectrical conductor.